In optical communications networks, optical transceiver modules are used to transmit and receive optical signals over optical fibers. On the transmit side of a transceiver module, a light source (e.g., a laser diode) generates amplitude modulated optical signals that represent data, which are received by an optics system of the transceiver module and focused by the optics system into an end of a transmit optical fiber. The signals are then transmitted over the transmit fiber to a receiver node of the network. On the receive side of the transceiver module, the optics system of the transceiver module receives optical signals output from an end of a receive optical fiber and focuses the optical signals onto an optical detector (e.g., a photodiode), which converts the optical energy into electrical energy.
The transmit and receive fiber cables have connectors on their ends, often LC connectors, that are adapted to mate with transmit and receive receptacles, respectively, formed in the transceiver module. A variety of optical transceiver module configurations are used in optical communications network. Some optical transceiver modules have multiple transmit receptacles and multiple receive receptacles for connecting multiple receive and transmit fiber cables to the module. Some transceiver modules having a single receive receptacle and a single transmit receptacle arranged side by side for connecting a single receive fiber cable and a single transmit fiber cable, respectively, to the transceiver module.
The transceiver modules themselves also have mating elements on them that are adapted to mate with mating elements formed on the cages. The cages are contained in racks, and each rack typically includes many cages that are arranged in very close proximity to one another. Each of these cages is configured to receive a transceiver module on the front side of the rack through a front panel of the rack. The transceiver modules are configured so that they may be inserted into and removed from the cages. The modules typically include latching mechanisms that couple to mating features on the cages when the modules are inserted into the cages. In order to remove a module from a cage, the module must be de-latched to decouple the latching mechanism from the features on the cage, which can be challenging when the modules are spaced closely together in the racks.
A variety of different latching mechanism configurations are used on optical transceiver modules. In general, latching mechanisms used on optical transceiver modules include spring loading elements that maintain the latching mechanisms in their locked positions via spring forces. These types of latching mechanisms typically include a bail that is moved to a locked position in order to latch the module to the cage and that is moved to an unlocked position in order to de-latch the module from the cage. When the bail is in the locked position, a latch lock pin extends through an opening formed in the cage to prevent movement of the module relative to the cage and relative to the LC connectors connected to the transmit and receive receptacles. When the bail is in the locked position, the latch lock pin is retracted from the opening formed in the cage, making it possible to remove the module from and insert the module into the cage.
The latching mechanism needs to provide sufficient “stiffness”, or rigidity, when in the locked position. When forces are exerted on the optical fiber cables, those forces are transferred from the cable to the LC connector attached to the end of the cable. The forces transferred to the LC connector are then transferred from the connector to the transceiver module housing, and then from the transceiver module housing to the latch lock pin and cage. If the latching mechanism is not sufficiently stiff when the bail is in the locked position, the forces that are transferred from the latch lock pin to the bail can result in unwanted movement of the LC connector relative to the transceiver module housing, and even in de-latching, or unlocking, of the latching mechanism. The resulting movement can cause electrical problems at the electrical connector. If sufficient force is applied, the latch may fail allowing the transceiver to come out of the cage causing an electrical disconnect and possible mechanical damage to the transceiver and cage.
Accordingly, a need exists for an optical transceiver module having a latching mechanism that is sufficiently stiff to prevent forces exerted on the latch lock pin from being translated to the bail.